A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether patients with haemophilia undergoing cardiac surgery have good surgical outcomes. Haemophilia A and haemophilia B are sex-linked recessive inherited diseases affecting males only, with females acting as carriers. The conditions result in various degrees of factor VIII or factor IX deficiency, respectively. The life expectancy of haemophilia patients is increasing and now approaches that of the general male population, and they are confronted with age-related co-morbidity, including ischaemic cardiovascular disease. Replacement of the deficient factor (VIII for haemophilia A and IX for haemophilia B) is the cornerstone of treatment; other therapeutic options include tranexamic acid, desmopressin and aprotinin. Recently, the advent of recombinant factor VIII and IX has eliminated the infective risk of using factor concentrates, such as prothrombin complex concentrate or fresh frozen plasma. A total of 84 papers were found using the reported search criteria, and out of this 25 papers, selected with reference to a more modern date range, provided the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results were tabulated. We conclude that there is lack of good-quality evidence and that, in all probability, these papers are subject to publication bias as poor outcomes are unlikely to have been reported. However, all the reported series showed that good outcomes are possible in this specific subgroup of patients given the correct approach. The data accrued from these studies (a total of 30 adults and three children) suggest that routine cardiac surgery can be performed safely in patients with haemophilia, with minimal morbidity and mortality. We identified the following key points to achieve this result: a team approach, a factor replacement protocol and perioperative monitoring of factor levels. Intraoperative plasma factor levels can be easily measured before heparin and after protamine sulphate administration, whereas during cardiopulmonary bypass this will require a chromogenic method. Exposure to factor concentrates early in the life might predispose a patient with severe haemophilia to the development of inhibitors. Moreover, the absence of inhibitors should be confirmed before any surgical procedure.